Currently, semiconductor manufacturing technology has been highly integrated to be 10 nm or less and has been continuously developing. Owing to the high-integration, the line width becomes narrow in the production of silicon wafers used in producing a semiconductor, and change in patterns, temperature, silicon consumption, etc. become very important factors.
Generally, a cleaning method using hydrogen peroxide (H2O2) or a cleaning method using ozone (O3) is used in a wafer. The cleaning method using hydrogen peroxide (H2O2) is a method to remove particles by mixing hydrogen peroxide, ammonia, and pure water, and the cleaning method using ozone (O3) is a method to remove organic material by mixing ozone with sulfuric acid.
However, if the cleaning method using hydrogen peroxide and the cleaning method using ozone are used, oxygen in the cleaning liquid is reacted to the wafer silicon to generate chemical oxide. Therefore, in order to remove the chemical oxide, it has been adopted a method to etch the surface of the wafer using hydrogen fluoride at the last step of cleaning.
However, although the method to etch the surface of the wafer using hydrogen fluoride at the last step is used, the oxide is also defected from the surface of the wafer. In particular, the method to use the hydrogen fluoride at the last step causes a problem in a fine process of 90 nm or less.
In particular, after cleaning, the silicon consumption of 1 Å or less has been recently required. It means that the cleaning method using hydrogen peroxide and the cleaning method using ozone are not suitable for cleaning the wafer.